Final Flashcards
Complete dominance
The dominant allele has the same phenotypic effect whether present in one or two copies
Incomplete dominance
The appearance of the heterozygous hybrid falls between the phenotypes of the two homozygous parents
Codominance
Both alleles are expressed in heterozygous individuals and neither allele is masked by the other
(Different from incomplete dominance bc each trait in present separately)
(Ex. AB blood type)
Pleiotropy
One gene influences multiple characters
Ex. sickle cell anemia
Polygenic inheritance
Additive effects of two or more genes on a single phenotypic character
(Opposite of pleiotropy)
Law of independent assortment
Inheritance of one character has no effect on the inheritance of another
Each pair of alleles sorts independently of other pairs of alleles during gamete formation
Physical basis in the orientation of homologous chromosome pairs in metaphase I
Law of segregation
A sperm or egg cell carries only one allele for each inherited character bc alleles pairs separate during the production of gametes
Physical basis in the separation of homologues in anaphase I
Linked genes
Genes located on the same chromosome, close together tend to be inherited together
Do not follow law of independent assortment
wild type
The traits most common in nature
Recombinant
Coming from two or more sources
Testcross
a mating between an individual with an unknown genotype with an homozygous recessive individual
Dihybrid
Dihybrid cross
heterozygous for both characters (RrYy)
Crossing these individuals with one another
recombination frequency
Percentage of recombinant offspring in a generation
In linked genes, most offspring have parental phenotypes but some are recombinant (crossing over of heterozygous alleles)
alleles
alternative versions of genes
somatic cell
typical body cell containing 46 chromosomes
homologous chromosomes
a pair of matching chromosomes that are twins in length and centromere position, carry genes controlling the same inherited characteristics
two chromosomes of a homologous pair may have different versions of the same gene
locus
position on a chromosome where a particular gene is
autosomes
non sex chromosomes found in 22 pairs in all humans
diploid
all body cells contain 23 (in humans) pairs of homologous chromosomes
diploid number = 2n, 2n = 46
gametes
sex cells containing a single set of chromosomes, 22 autosomes plus a sex chromosome
haploid
sex cells contain 23 single chromosomes (one member of each homologous pair)
haploid number = n, n = 23
fertilization
haploid sperm cell fuses with a haploid egg cell
zygote
fertilized egg is diploid, one set of homologous chromosomes from each parent
23 maternal and 23 paternal chromosomes
Activator proteins and enhancers
Activator proteins bind to other transcription factor proteins and enhancers and then bind as a complex at the genes’ promoter to facilitate the correct attachment of RNA polymerase = increased transcription = increased gene expression
Transcription factors
proteins that assist eukaryotic RNA polymerase in gene expression
Repressor proteins and silencers
Repressor proteins bind to DNA sequences called silencers and inhibit the start of transcription = decrease gene expression
Photorespiration
Plants close their stomata when it is hot and dry to avoid losing water. They can’t bring in CO2 and O2 builds up. Rubisco adds O2 instead of CO2 to RuBP
Barr body
inactive X chromosome condensed
Homeotic gene
master control gene that regulates batteries of other genes that actually determine the anatomy of parts of the body
Signal transduction pathway
series of molecular changes that converts a signal on a target cell’s surface to a specific response inside the cell
The Central Dogma of DNA
DNA template Strand—>TRANSCRIPTION—> mRNA —> TRANSLATION —> Protein
karyotype
ordered display of magnified images of an individual’s chromosome arranged in pairs
-produced from dividing cells arrested at metaphase of mitosis
Euploid and Aneuplod
Normal chromosome number
Cells with extra or missing chromosomes
haploid gamete + haploid gamete
ziploid
unfertilized eggs are….
haploid(n)
fertilized eggs
diploid (2n)
trisomy 21
down syndrome
when there is an extra chromosome in pair 21
nondisjunction
failure of chromosomes or chromatids to separate normally during meiosis.
meiosis 1 in anaphase
meiosis 2 in anaphase
monohybrid cross
cross between 2 individuals differing in a single character
Lysogenic cycle
Phages DNA remains dormant in the bacteria’s DNA until triggered
Lytic cycle
The phage DNA hijacks the bacteria DNA to produce phages until there are so many that the bacterial cell lyses and phages live on
Transformation
One bacteria takes up and crosses over DNA with a dead bacteria
Transduction
Phages insert another bacteria’s DNA into a different bacteria by accident
Conjugation
Sex bridge - two bacteria switch DNA
Translocation
Non homologous chromosome segments swap places - causes leukaemia or some other bad thing
